Variable orifice gas washer



June 15, 1965 F. H. REHMUS 3,139,332

VARIABLE ORIFICE GAS WASHER Filed May 2, 1962 2 Sheets-Sheet 1 Fig. I.

INVENTOR.

FREDERICK H. REHMUS his ATTORNEY June 15, 1965 .F. H. REHMUS 3,

' VARIABLE oRIFIcE'c-As WASHER Filed May 2, 1962 Y 2 Sheets-Sheet 2 FREDERICK H. REHMUS his ATTORNEY United States Patent 3,189,332 VARIABLE ORIFICE GAS WASHER Frederick H. Rehmus, Whitehall, Pa, assignor to Jones &

Laughiin Steel Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed May 2, 1962, Ser. No. 191,838 9 Claims. (Cl. 261-62) 1 This invention relates to gas washers and more particularly to gas washers suitable for cleaning gas from iron blast furnaces.

Application Serial No. 839,030, filed by R. W. Davy, I. S. Arnold, and S. Vajda, now Patent Number 3,067,991, discloses a blast furnace gas washer which comprises an orifice plate positioned across a duct through which the blast furnace gas is conducted, and one or more water pipes positioned around the duct upstream of the orifice plate to discharge wash water into the gas stream. The constriction in the duct provided by the orifice plate creates a very substantial pressure drop across the washer, and the efiiciency of the gas washer in removing dirt particles from the gas is related to that pressure drop. That gas washer is well suited for use with a blast furnace operated at a super-atmospheric top pressure, as the washer itself can be adjusted to throttle the furnace the desired amount.

The area of the orifice in the gas washer above mentioned is necessarily fixed, and the throttling effect of the washer on a blast furnace or other apparatus connected thereto is likewise fixed. It is well known, however, that the smelting of iron in a blast furnace usually proceeds at a rate dictated by burden permeability or economic considerations, thus generating larger quantities of gas at some times than at others. Several hours are required for the constituents of the burden to work their way downwardly from the top of the furnace into its hearth, and this movement of the burden may be faster at some times than at others. Likewise, the course taken by the blast from the tuyeres up through the burden to the top of the furnace is subject to change as the burden shifts in its downward movement. The result of these variables, and others familiar to those skilled in the art of iron smelting, is that the gas discharged from a blast furnace fluctuates in pressure and volume. The top pressure will necessarily fluctuate undesirably in such a furnace which is throttled by an orifice of fixed area.

An object of my invention, therefore, is to provide a gas washer of the orifice-plate type which is capable of manual or automatic adjustment to maintain substantially constant pressure drop across the device on a blast furnace or other apparatus to which it is connected. It is another object of my invention to provide such a gas washer with a variable area orifice. It is another object to provide a gas washer as above described with an orifice the area of which can be varied by simple rotary movement. It is still another object of my invention to provide a variable gas washer in which the pressure drop across the washer varies substantially linearly with rotation of the variable element. Other objects of my invention will appear in the course of the following description thereof.

An embodiment of my invention presently preferred by me is illustrated in the attached figures to which reference is now made.

FIGURE 1 is an elevation, partly broken away, of the apparatus of my invention.

FIGURE 2 is a horizontal cross section through the apparatus of FIGURE 1 taken on the plane IIII.

FIGURE 3 is an elevation in section through a portion of the apparatus of FIGURE 1 taken on the plane III-III.

FIGURE 4 is a detail view of the manual adjusting means for my variable orifice.

FIGURE 5 is a graph of pressure drop across my gas washer plotted against the rotation of the variable wedge in degrees.

In the figures a gas discharge pipe 1 is connected to the upper end of an upright cylindrical duct 2. The lower end 3 of duct 2 projects into a larger diameter closed shell 4. The upper end of shell 4 is connected to duct 2 by a tapered shoulder ring 5. The lower end of shell 4 is closed by a conical head 6. The small end of head 6 is provided with a clean-out door '7 mounted on a lever arm 8 which is pivoted on a bracket 9. An overflow pipe id is connected into the small end of head 6 and at its other end is elongated into an inverted U pipe 11 which forms a barometric leg. A gas discharge pipe 12 opens out of the side of shell 4 at a level somewhat above that of lower end 3 of duct 2. A water inlet 13 is provided through the side of shell 4.

Duct 2 is split horizontally above shoulder 5 and is provided at the split with an upper flange 15 and a mating lower flange 16. Between flanges 15 and 16 is positioned a flat plate 17 provided with a centrally located circular orifice 18. Above flange 15 duct 2 is encircled with a header pipe 19 which is connected to a source of wash water, not shown. From header pipe 19 elbows 20 and 21 extend downwardly and connect with open end delivery pipes 22 and 23 respectively, the open ends of which extend through the wall of duct 2 at opposite ends of a diameter thereof. Those delivery pipes 22 and 23 are positioned upstream of flange 15.

Positioned downstream of flange 16 is a horizontal shaft 24 which extends across a diameter of duct 2 and through the shell of the duct at each side. The opposite ends of shaft 24 are journaled in bearings 25 and 26 respectively. Bearing 25 is provided with a protective cover 27 and bearing 26 is provided with a like protective cover 28. End 29 of shaft 24 extends through protective cover 27 and is attached to means, to be described, adapted to rotate shaft 24.

Centrally affixed to shaft 24 Within duct 2 is a cylindrical wedge 30 which comprises plane sides 31 and 32 inclined to each other, and cylindrical wall 33 which tapers from a minimum thickness 34 where the plane sides 31 and 32 approach each other to a maximum thickness 35 where those sides are farthest apart. Shaft 24, which passes through the center of wedge 30 along its axis, is spaced below orifice plate 17 a distance equal to the radius of wedge 30. The thick end 35 of wedge 30 is of lesser width than orifice 13. The thin edge of wedge 34 is about the thickness of plate 17, and the diameter of wedge 30 is about that of orifice 18.

My means for rotating shaft 24 and attached wedge 30 comprise lever arm 37 which is affixed to end 29 of shaft 24. Lever arm 37 carries a. counter-weight 38 adjusted to counterbalance the extra weight of thick end 35 of wedge 30. Adjacent lever arm 37 is positioned an upright fixed sector 3h provided around its circumference with a plurality of spaced holes 40-40. Lever arm 37 is likewise provided with a hole 41 which aligns itself with successive holes 40 as shaft 24 is rotated. A pin 42 is inserted through hole 41 and aligned hole 40 to lock shaft 24 and wedge 30 in any one of a number of positions predetermined by the locations of holes 4tl4t).

The operation of my apparatus is evident from the foregoing description. Water is admitted through pipe 13 to form a water bath in the bottom of shell 4, the height of which bath cannot exceed the height of the inverted U 11. The gas to be cleaned, from a blast furnace or other source, is conducted from pipe 1 into the upper end of duct 2. As it passes downwardly through duct 2, it comes in contact with wash water discharged transversely of the gas stream from pipes 22 and 23. The stream of gas and wash water must pass through the constriction caused by orifice 18, and this results in the acceleration of the gas stream and the creation of very substantial atomization in this area which brings about intimate contact between the atomized water and the dirt particles in the gas stream. As the gas stream carrying the now wetted particles of dirt continues its flow through duct 2 and out the lower end 3 thereof into shell 4, the gas loses some of its velocity and finds its way out through discharge pipe 12. The wetted dirt particles, however, coalesce and continue to fall into the water bath in conical head 6 of shell 4, from which they are removed from time to time through clean-out door 7.

It will be observed that the effective area of orifice 18 is varied by rotation of shaft 24 and wedge 30 aifixed thereto. When wedge 30 is in the position shown in FIGURES 2 and 3 with its thin end 34 adjacent orifice 18 that orifice has its maximum effective area. When shaft 24 is rotated through 180, thick end 35' of wedge 30 is rotated into position adjacent orifice 18 and the effective area of the latter is then at a minimum. The effective area of orifice 18 may be adjusted between those maximum'and minimum values by rotating wedge 30 a greater or lesser amount. FIGURE shows a typical change in permanent pressure drop across the orifice with the change in degree of rotation of the wedge 50 for one embodiment of my invention. The pressure drop is measured in inches of water. Zero degrees on the abscissa corresponds to the position of wedge 30 shown in FIGURES 2 and 3, and 180 corresponds to the position of wedge 30 bringing about the greatest reduction in effective area of orifice 18. The curve of FIGURE 5 is seen to be substantially linear for the dial setting range between 70 and 160 which corresponds to a desirable pressure range for my gas washer when it is used in conjunction with an iron blast furnace. By suitable dimensioning of orifice 18 and wedge 30 I can adjust my apparatus to provide other ranges or pressure drop for any gas rate.

I claim:

1. A gas washer comprising a duct, means for introducing dirty gas into the duct, a partition across the duct provided with a central orifice, means positioned upstream of the partition for introducing washing liquid into the duct, means connected to the duct downstream of the partition for separately collecting clean gas and dirty washing liquid, a rotatable shaft positioned transversely of the duct, means for rotating the shaft, and a cylindrical wedge fixed to the shaft adjacent the orifice and adapted to vary the orifice area as the shaft is rotated by varying the portion of the circumferential wall of the wedge adjacent the orifice.

2. A gas washer as in claim 1 in which the rotatable shaft is positioned downstream of the partition.

3. A gas washer as in claim 1 in which the duct is cylindrical and the rotatable shaft is positioned on a diameter of the duct.

4. A gas washer as in claim 1 in which the wedge is a cylindrical wedge and the rotatable shaft passes through the wedge along its axis.

5. A gas washer as in claim 1 in which the wedge is a cylindrical wedge, the rotatable shaft passes through the wedge along its axis, and the rotatable shaft is spaced from the partition a distance substantially equal to the radius of the cylindrical wedge.

6. A gas washer as in claim 1 in which an end of the rotatable shaft extends outwardly of the duct and is provided with means for locking the shaft in any one of a plurality of predetermined positions of rotation.

7. A gas washer as in claim 1 in which the partition is normal to the duct axis, the rotatable shaft bisects the orifice and the wedge is cent-rally located on the shaft.

8. A gas washer as in claim 1 in which the wedge is a cylindrical wedge having plane sides.

9. A gas washer as in claim 1 in which the orifice is circular and the wedge is a cylindrical wedge of a diameter substantially that of the orifice.

References (fitted by the Examiner UNITED STATES PATENTS 527,573 10/94 Wilson 126297 1,102,380 7/14 Alberger 261-116 X 1,718,988 7/29 Stewart 261118 2,315,227 3/43 Rohlin et a1 261118 X 2,621,754 12/52 Doyle.

2,801,647 8/57 Dorrel et a1. 138-46 2,934,311 4/60 Sjoholm 251209 2,964,304 12/60 Rice 261-418 3,067,991 12/62 Davy et al 2611 18 X HARRY B. THORNTON, Primary Examiner. HERBERT L. MARTIN, Examiner. 

1. A GAS WASHER COMPRISING A DUCT, MEANS FOR INTRODUCING DIRTY GAS INTO THE DUCT, A PARTITION ACROSS THE DUCT PROVIDED WITH A CENTRAL ORIFICE, MEANS POSITIONED UPSTREAM OF THE PARTITION FOR INTRODUCING WASHING LIQUID INTO THE DUCT, MEANS CONNECTED TO THE DUCT DOWNSTREAM OF THE PARTITION FOR SEPARATELY COLLECTING CLEAN GAS AND DIRTY WASHING LIQUID, A ROTATABLE SHAFT POSITIONED TRANSVERSELY OF THE DUCT, MEANS FOR ROTATING THE SHAFT, AND A CYLINDRICAL WEDGE FIXED TO THE SHAFT ADJACENT THE ORIFICE AND ADAPTED TO VARY THE ORIFICE AREA AS THE SHAFT IS ROTATED BY VARYING THE PORTION OF THE CIRCUMFERENTIAL WALL OF THE WEDGE ADJACENT THE ORIFICE. 